Descriptor guided fast marching method for analyzing images and systems using the same

ABSTRACT

Methods and systems for descriptor guided fast marching method based image analysis and associated systems are disclosed. A representative image processing method includes processing an image of a microelectronic device using a fast marching algorithm to obtain arrival time information for the image. The arrival time information is analyzed using a targeted feature descriptor to identify targeted features. The detection of defects is facilitated by segmenting the image. The segmented image can be analyzed to identify targeted features which are then labeled for inspection.

TECHNICAL FIELD

The present technology is directed generally to descriptor guided fastmarching method for analyzing images and associated systems.

BACKGROUND

Manufacturers of microelectronic devices are continually reducing thesize and increasing the density of components in integrated circuits toincrease the speed and capacity of devices and reduce the powerconsumption. Complex series of manufacturing protocols, inspectionprotocols, and testing protocols are often performed to producemicroelectronic devices, such as light-emitting diodes (LEDs),integrated circuits, and microelectromechanical systems (MEMS). It maybe difficult to rapidly and accurately detect defects in microelectronicdevices. For example, microelectronic devices often include circuitrywith vias that are formed by depositing conductive material intoopenings (e.g., through-holes) in wafers. The conductive material maydeposit faster at the edges of the openings than within the holes, andthe build-up of conductive material at the openings may inhibitdeposition of conductive material at central regions of the holesresulting in voids or other defects. These voids are commonly referredto as keyholes. A scanning electron microscope (SEM) image can bevisually inspected to locate and identify keyholes. However, it isdifficult to locate and accurately identify keyholes because SEM imagesoften have significant noise and low contrast, and keyholes often varyin size and shape.

Conventional automated systems can compare patterns to identify defects.For example, a conventional automated system can compare a pattern in acaptured image to a reference pattern and identify defects based on thecomparison. Conventional automated systems can also measure criticaldimensions that are necessary to the function of the component.Unfortunately, reference patterns or critical dimensions have to beknown before performing pattern comparison or critical dimensionmeasurements. Additionally, detection rates of potential defects usingpattern comparison or critical dimension measurements can decreasesignificantly when analyzing images with irregular shaped features(e.g., keyholes), significant noise, and low-contrast.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an image of a microelectronic device with featuresidentified in accordance with an embodiment of the present technology.

FIG. 2 is a flowchart for processing an image in accordance with anembodiment of the present technology.

FIG. 3 illustrates an image of a portion of a microelectronic devicewith an array of vias.

FIG. 4 illustrates an image before correction processing.

FIG. 5 illustrates a preprocessed image in accordance with an embodimentof the present technology.

FIG. 6 illustrates a preprocessed image in accordance with an embodimentof the present technology.

FIGS. 7-9 illustrate stages of a fast marching method in accordance withan embodiment of the present technology.

FIGS. 10-13 illustrate starting areas for fast marching methods inaccordance with an embodiment of the present technology.

FIGS. 14-18 illustrate a process for producing an arrival time image inaccordance with an embodiment of the present technology.

FIG. 19 illustrates a processed image of a portion of a microelectronicdevice in accordance with an embodiment of the present technology.

FIG. 20 is a plot of distance versus intensity for the image of FIG. 18in accordance with an embodiment of the present technology.

FIGS. 21 and 22 illustrate segmented images in accordance withembodiments of the present technology.

FIG. 23 illustrates an arrival time image of a via with a defect inaccordance with an embodiment of the present technology.

FIG. 24 illustrates a segmented image of the via of FIG. 23 inaccordance with an embodiment of the present technology.

FIG. 25 illustrates a segmented arrival time image of a via inaccordance with an embodiment of the present technology.

FIG. 26 illustrates an image of a microelectronic device with vias andpotential defects identified in accordance with an embodiment of thepresent technology.

FIG. 27 illustrates an image with potential stictions identified inaccordance with an embodiment of the present technology.

FIG. 28 illustrates an image with contacts within lines in accordancewith an embodiment of the present technology.

FIG. 29 illustrates an image processing system in accordance with anembodiment of the present technology.

DETAILED DESCRIPTION

Specific details of several descriptor guided image processing methodsand systems using the same are described below. In particularembodiments, the image processing methods are performed on images of amicroelectronic device. The images can be from an electron microscope(e.g., a scanning electron microscope (SEM), a transmission electronmicroscope (TEM), or the like), an optical imager (e.g., an opticalmicroscope, a camera, etc.), or other type of imaging equipment capableof capturing images for defect recognition, pattern recognition, or thelike. The term “image” generally refers to raw images, preprocessedimages, processed images, labeled images, and the like. The term “SEMimage” generally refers to an image produced by a SEM and may be ingrayscale or color. A person skilled in the relevant art will understandthat the technology may have additional embodiments, and that thetechnology may be practiced without several of the details of theembodiments described below with reference to FIGS. 1-29.

FIG. 1 illustrates a SEM image 100 with targeted features of amicroelectronic device identified using descriptor guided imageprocessing. The SEM image 100 can include boxes 110 that identify vias120 and boxes 130 that identify potential defects 132. The potentialdefects 132 can be visually inspected to determine, for example, whetherthe potential defects 132 are actual defects. The labeling can increaseidentifying accuracy and increase inspection throughput.

The vias 120 can be formed using a multi-step process, including formingan insulated opening (e.g., an insulated through-hole) in a substrate134. After forming the opening, a filling process (e.g., physical vapordeposition, chemical vapor deposition, sputtering, etc.) may beperformed to fill the opening with a conductive material. If theconductive material accumulates at the periphery of the opening in thesubstrate 134 faster than within the hole, a keyhole may be formed. Thepotential defect 132 in FIG. 1 is such a keyhole. The boxes 110, 130help a viewer conveniently locate and analyze the via 120 and potentialdefect 132. A box 137 identifies a properly formed via 138 (e.g., a viawithout a keyhole).

FIG. 2 is a flowchart for processing an image. Generally, a descriptorguided fast marching method 150 can include preprocessing an image(block 160), processing and image (block 162), performing a descriptorguided analysis (block 163), and outputting results (block 164). Thedescriptor guided fast marching method 150 can be performed to analyzedifferent types of images, including SEM images, TEM images, opticalimages (e.g., images from an optical microscope), or the like. Themagnification of the image may vary depending on the type ofmicroelectronic device (e.g., a substrate, a wafer, a diced wafer,integrated circuitry, semiconductor device, semiconductor die, LED,etc.) and the features (e.g., contacts, vias, runners, traces,electrodes, wires, solder balls, etc.) to be analyzed. Microelectronicdevices include, without limitation, light emitters (e.g., laser diodes,LEDs, etc.), processed wafers (e.g., wafers with circuitry), memory,MEMS structures, or the like.

At block 160, an image is preprocessed to produce a preprocessed image.Image preprocessing can include correction processing such as, withoutlimitation, intensity correction, color correction, saturationcorrection (e.g., color saturation correction), contrast correction,and/or tilt correction. A wide range of different types of filters,algorithms, and routines (e.g., data fitting routines) can be used forcorrection processing to increase the accuracy of descriptor basedanalysis, decrease image processing times, or achieve other results.Other types of imaging preprocessing can also be performed.

At block 162, the preprocessed image can be further processed using afast marching method to smooth data and generate arrival timeinformation that can include, without limitation, an arrival timefunction, an arrival time image, an arrival time matrix, or the like.The arrival time function can be a smooth, continuous function (e.g., adifferentiable function, a monotonic function, etc.) suitable forcontour analysis (e.g., intensity contour analysis, color contouranalysis, etc.), segmentation (e.g., segmentation based on one or moredescriptors), or the like. The arrival time image can be inspected toidentify targeted features, such as potential defects, structuralfeatures, electrical features, etc. The arrival time image can bevisually inspected by, for example, a technician, a wafer inspector, oran engineer. Additionally or alternatively, an automated system caninspect the arrival time image. The arrival time matrix can be analyzedusing statistical techniques, numerical techniques, or the like. In someembodiments, the fast marching method uses different fast marchingalgorithms to process different targeted features. The targeted featurescan include, without limitation, patterns, potential defects (e.g.,stiction, keyholes, cracks, improperly formed bond pads, etc.), edges(e.g., edges of cleaved or singulated LEDS), boundaries, or the like.

The fast marching method can process images without having informationabout the image. For example, the fast marching method can start at highintensity areas (e.g., light areas) of an image that may correspond toareas surrounding a potential defect and move towards low intensityarea(s) (e.g., dark areas) that may correspond to the potential defect.As the fast marching method moves towards low intensity area(s), thefast marching method can detect a boundary of the potential defect. Inother embodiments, the starting areas can be in low intensity areas ofan image and move towards high intensity area(s) to detect a boundary ofthe potential defect. In some embodiments, starting areas are in aportion of an image having a uniform intensity such that the fastmarching method identifies intensity variations as boundaries ofpotential defects (e.g., regular shaped defects, irregularly shapeddefects, etc.).

In some embodiments, the fast marching method can identify and/oranalyze the interior regions of contacts or vias. For example, toidentify interior areas of vias, a raw image can be processed to producean arrival time image representative of the vias. The fast marchingmethod can process such raw images to identify the interior areas ofvias without having information about the image.

At block 163, a descriptor guided analysis can be used to identifytargeted features based on a targeted feature descriptor. The targetedfeature descriptor can include a segmentation algorithm that performssegmentation using on one or more criteria (e.g., a threshold value,mean, mode, median, rate of change, standard deviation, etc.) based on,for example, intensity, color coordinators, or the like. Additionally oralternatively, the targeted feature descriptor can include a defectdescriptor algorithm used to identify potential defects whereas apattern descriptor can be used to identify patterns (e.g., a regularpattern, an irregular pattern, etc.). Defects can include, withoutlimitation, holes (e.g., voids, keyholes, etc.), stictions, improperlypositioned features, misaligned features, substrate defects (e.g.,defects in unprocessed wafers, processed wafers, etc.), or the like.

The fast marching method can take image intensity of an image as a speedfunction and convert it into arrival time information to, for example,reduce, limit, or substantially eliminate noise, identify/analyzeselected features (e.g., edges of vias, edges of contacts, edges ofrunners, or the like), or the like. The targeted feature descriptor canbe used to determine the arrival time mark of reaching a predeterminedarea corresponding to the area of the targeted feature. The arrival timemark can define the domain of each feature to enable identification ofinternal areas of the features that exhibit significant acceleration.For example, if more than a predetermined number of neighboring pixelsor cells within a predetermined area show significant acceleration(e.g., acceleration at or above a threshold level), the pixels or cellscan be identified as a potential defect. Additionally or alternatively,a set of edge vectors (with or without offset tolerance) can be used toanalyze patterns, such as irregular patterns and regular patterns. Insome embodiments, a set of edge vectors can be used to separate anirregular pattern from a regular pattern at the same general areaintensity level.

At block 164, the results of the descriptor guided analysis areoutputted and can include, without limitation, labeled images,statistics, correction routines, optimization routines, reports, or thelike. The labeled images can be labeled raw images, labeled preprocessedimages, labeled processed images, or the like. The labels can be boxes,highlighting, annotation, or other types of indicators for identifyingfeatures or areas for visual inspection, automated inspection, or thelike. The statistics can include, without limitation, across-waferstatistics, batch statistics, wafer-to-wafer statistics, or the like.The correction routines can be used to adjust processing parameters(e.g., processing parameters for deposition equipment, processingparameters for CMP equipment, etc.) to reduce the frequency of defects,increase throughput, or otherwise enhance processing. The reports caninclude, without limitation, characteristics of identified features,statistics, alignment information, or the like.

FIG. 3 illustrates a SEM image 169 of a microelectronic device withcolumns 170 a, 170 b, 170 c, 170 d (collectively 170) with spaced apartvias. The diameters of the vias can be in a range of, for example, about0.1 μm to about 0.25 μm. Because keyholes may have diameters less thanabout 0.01 μm and may vary in shape and size, it may be difficult torapidly and accurately identify keyholes. For example, a viewer may havedifficulty in identifying a keyhole 174 a in via 172 a, whereas via 172b does not have such a defect.

FIGS. 4 and 5 show stages of an embodiment of processing a SEM image.FIG. 4 shows a SEM image 178 that includes intensity variations whichcan result in a relatively dark region 179 (indicated by a dashed line180). FIG. 5 shows a preprocessed image 178′ in which noise has beenremoved for a substantially uniform background intensity to increase theaccuracy of subsequent image processing.

FIG. 6 illustrates an example of a preprocessed image 169 in accordancewith an embodiment of the present technology. The vias (e.g., via 172)in the preprocessed image 169 can have well-defined boundaries. The fastmarching method can convert the preprocessed image 169 to an arrivaltime image.

FIGS. 7-9 show examples of stages of the fast marching method. The fastmarching method can generally include identifying at least one startingarea and marching through one area (e.g., a cell, a pixel, etc.) at atime to determine arrival information for non-starting areas in a mannerthat converts intensity of different regions of an image to arrival timeinformation. The fast marching method can process an entire image or aportion thereof.

Referring to FIG. 7, ten frozen areas are represented by solid dots 200.Each dot 200 can be one or more pixels or cells in which arrival timeinformation has been determined. The twelve adjacent circled unfrozendots represent candidate dots within a narrow band suitable for movementof a wave-front 210. A wave front algorithm can be used to solve aboundary value equation to determine arrival time information (e.g.,arrival time, acceleration, etc.) at each candidate dot. In someembodiments, the boundary value equation can be an Eikonal equationdescribing the movement of the wave front 210 according to the equation:

R|∇T|=1  (Equation I)

where R is a rate (speed function) at (x, y) of an image and T is thearrival time at (x, y) of the image. The rate (speed function) can bethe intensity of a cell or a pixel at a location (x, y) of the image.

Referring to FIG. 8, the movement of the wave front 210 to a candidateunfrozen dot or a live dot (shown as circles with open centers) can bedetermined based on whether that candidate unfrozen dot corresponds tothe fastest arrival time. The unfrozen dot 212 of FIG. 8 has the fastestarrive time. FIG. 8 shows the dot 212 after it has been frozen. Arrows214, 216 indicate two non-frozen neighboring dots 218, 219. FIG. 9 showscandidate dots 218, 219 (circled in dashed lines) selected for the nextiteration. The circled dots in FIG. 9 are analyzed to determine whichcircled dot has the fastest arrival time. In this manner, the fastmarching method can work outwardly away from frozen areas.

Because boundaries of the targeted features may be identified by suddenchanges in intensity, starting areas can be spaced apart from suddenchanges in intensity. In some images, keyholes may appear as black dotswhereas the upper surfaces of vias may be light gray or some otherhigher intensity. The fast marching method can move away from startingareas in high intensity regions surrounding the keyhole to areas of lowintensity in the keyholes. This helps ensure that boundaries of thekeyholes are accurately detected. By way of example, the dots 200 ofFIG. 7 can correspond to a portion of the via surrounding a keyhole. Thewave front 210 can move towards and across the boundary of the keyhole.Alternatively, the dots 200 of FIG. 7 can be located in an areacorresponding to a keyhole.

FIGS. 10-13 illustrate examples of different patterns of starting areasfor producing an arrival time image that is representative of featuresin an image. The grids can be filled with data obtained using the fastmarching method to produce an arrival time image corresponding to animage (e.g., an image serving as a rate function of the Eikonalequation). FIG. 10 shows a grid 220 that has fifteen rows and fifteencolumns of cells each containing a dot or point. Distances between cellsof the grid 220 can be determined using the dots or points. An upper row222 has frozen arrival time starting areas (illustrated as filled areas)or frozen dots. The row adjacent the upper row 222 can be a narrow bandof candidate cells for the fast marching method discussed in connectionwith FIGS. 7-9. Arrival times are used to fill in the unfrozen areas(illustrated as unfilled or empty areas) of the grid 220. For example,each cell of the grid 220 can be filled with an arrival time that iscalculated based on the intensity in a corresponding cell in a processedimage to create an arrival time image. An example fast marching methodfor producing an arrival time image is discussed in connection withFIGS. 14-22.

Referring to FIG. 11, starting areas 230 surround non-starting areas240. The fast marching method can work away from the starting areas 230,as indicated by arrows 232, 234, 236, 238. Referring to FIG. 12,starting areas 240 define four groups 250 a, 250 b, 250 c, 250 d(collectively 250) of non-starting areas. Each group 250 has thirty-sixnon-starting areas 250. FIG. 13 shows an upper row 260 of starting areasand a spaced apart array 262 of starting areas. The number of startingareas, spacing of starting areas, dimensions of starting areas (e.g.,width, length, etc.), shapes of starting areas (e.g., square,rectangular, triangular, etc.), and pattern of starting areas can beselected based on, for example, the characteristics of features to beidentified and characteristics of the image to be analyzed. For example,starting areas can be selected to minimize, limit, or substantiallyeliminate a distance effect such that the calculated arrival time isbased primarily or entirely on intensity.

FIGS. 14-18 illustrate examples of stages of a process of evaluating akeyhole. FIG. 14 shows a preprocessed image of the via 172 a and thekeyhole 174 a. FIG. 15 illustrates a preprocessed image 280 of a portionof the keyhole 174 a and a grid superimposed on the preprocessed image.FIG. 16 shows a partially filled arrival time image. FIG. 17 shows fivestages of producing an arrival time image. FIG. 18 shows an arrival timeimage corresponding to the preprocessed image 280 of FIG. 15.

Referring to FIG. 15, the image 280 has a high intensity region 282 anda low intensity region 284. In this example, the low intensity region284 corresponds to a portion of the keyhole 174 a, and an upper row 286of cells can be selected as starting areas. Arrival times can bedetermined by setting the starting areas initial starting arrival time=0and the other areas arrival time=∞ to solve an Eikonal equation (see,e.g., Equation I above) based on the image 280 serving as a rate orspeed function. Cells in the upper row 290 of FIG. 16 are filled torepresent the arrival time=0. The filled cells in the upper row 290 arereferred to as “arrival time starting areas.” The fast marching methodcan sequentially work outward from the starting areas to convert theintensity of the cells in the preprocessed image 280 of FIG. 15 toarrival times used to fill corresponding cells of the arrival time image310 of FIG. 16. The filled cells of FIG. 16 are referred to as an“arrival time starting areas.” A row 287 in FIG. 15 can be the narrowband of candidate cells for the next iteration of the fast marchingmethod.

Referring to FIG. 17, the image 310 shows arrival times for the arrivaltime starting areas in the row 290. Image 312 shows cells filled witharrival times using the fast marching method that moves uniformly awayfrom the starting areas of the row 290. Image 314 shows cells filled bythe fast marching method working outwardly towards the high intensityareas of the image 280 (FIG. 15). After filling the cells correspondingto high intensity areas, the fast marching method moves towards the lowintensity areas of image 280 (FIG. 15). Image 316 shows cells filled asthe fast marching method moves in the direction indicated by arrow 319.Image 317 shows all of the cells filled with calculated arrival timesand is referred to as an “arrival time starting areas.” FIG. 18 showsthe arrival time image 317 in which an arrow indicates the direction inwhich measurements are taken for descriptor guided analysis. The arrivaltime image 317 is representative of the image 280 in FIG. 15.

FIG. 19 illustrates an arrival time image 324 generated using the fastmarching method. The arrival time image 324 can be the time function andthe image 280 can be a rate function of the Eikonal equation. The entireimage 324 can be produced using a single fast marching routine. In otherembodiments, each via can be identified using a separate fast marchingroutine. Each identified via can be separately analyzed to identifydefects in the respective via. The fast marching routines foridentifying vias can be different from fast marching routines used toidentify defects in the vias. For example, the resolution of the fastmarching method for analyzing internal areas of the vias can be higherthan the resolution of the fast marching method used to identify thevias. By way of example, dimensions of cells in the grid used to detectvias can be larger than the cells in the grid to detect keyholes in thevias.

FIG. 20 is a plot of distance versus intensity for the image 317 of FIG.18. The intensity of the cell 321 of FIG. 18 is between 0 and 25 atdistance 0 measured along the arrow of FIG. 18. The intensity begins toincrease at a distance of about 125 corresponding to a cell 323 of FIG.18. The rate of change in intensity generally increases from a distanceof about 125 to about 190. The rate of change in intensity decreasesfrom a distance equal to or greater than about 210. A smooth andcontinuous arrival time curve 331 corresponds to function that isdifferentiable at each point along the curve 331. In some embodiments,numerical techniques are used to generate the curve from the arrivaltime image data. The numerical techniques can include, withoutlimitation, curve fitting techniques (e.g., linear regression, higherorder polynomial fitting, exponential fitting, nonlinear fittings,etc.), interpolation, etc.

FIGS. 21 and 22 illustrate examples of segmented images generated usinga descriptor. Generally, a descriptor can have a segmentation algorithmthat utilizes threshold. A descriptor with two thresholds can be used togenerate the segmented image 400 of FIG. 21. A descriptor with onethreshold can be used to generate the segmented image 402 of FIG. 22.

Referring to FIGS. 20 and 21, a descriptor in the form of a targetedfeature descriptor 327 can have segment thresholds 337, 339 atintensities of about 540, 870, respectively. The segment thresholds 337,339 of FIG. 20 that define a first region 340, a second region 342, anda third region 344 in the image 400 of FIG. 21. The first region 340corresponds to the portion of the image 317 of FIG. 18 with intensitiesless than 540. The second region 342 in FIG. 21 corresponds to theportion of the image 317 of FIG. 18 with intensities between 540 and870. The third region 344 in FIG. 21 corresponds to the portion of theimage 317 of FIG. 18 with intensities greater than about 870. The secondregion 342 can be identified as a potential keyhole.

The descriptor in the form of a targeted feature descriptor 341 can havea segmented threshold of about 410. FIG. 22 illustrates an image with afirst region 350 and a second region 352 defined by the descriptor 341.The first region 350 corresponds to the portion of the image 317 of FIG.18 with intensities equal to or less than 410. The second region 352corresponds to the portion in the image 317 of FIG. 18 with intensitiesgreater than 410.

Descriptors can have a number of thresholds that are selected based on,for example, the number of targeted features to be identified. Forexample, a first threshold can be used to detect boundaries of a contactor a via. A second threshold can be used to detect potential defectswithin the contact or via. Different descriptors can identify differenttargeted features. A stiction descriptor can detect potential stiction,an alignment descriptor can detect alignment of features, and a patterndescriptor can detect patterns. A single image can be analyzed usingdifferent descriptors. Additionally, different descriptors can be usedto process different types of images. For example, a first descriptorcan be used to analyze an SEM image from a manufacturer and a seconddescriptor can be used to analyze an SEM image from anothermanufacturer. The descriptors can compensate for differences inintensities between different imaging equipment. A descriptor can alsobe modified based on prior inspections (e.g., inspection ofmicroelectronic devices, inspection of a wafer, inspection of a batch ofwafers, etc.). This can increase the accuracy of the analysis and alsomay reduce inspection times.

FIG. 23 shows another example of an arrival time image 420 of the via172 a and keyhole 174 a. A descriptor can be used to determine whetherthe cells or pixels correspond to a potential defect based on selectioncriteria. The selection criteria can be, for example, based on athreshold acceleration. The number of cells or pixels within theboundary of the via 172 a (or other region of interest) that are at orabove the threshold acceleration can be identified as discussed inconnection with FIGS. 24 and 25.

FIG. 24 shows a segmented image of the keyhole 174 a. The dark regionscorrespond to areas of the via 172 a with an acceleration less than thethreshold acceleration (e.g., an acceleration determined based on thearrival time image) of selection criteria and light pixels for allpixels or cells with an acceleration equal to or greater than thethreshold acceleration of the selection criteria. The descriptor guidedanalysis can have a selection routine based on the number and positionof the cells or pixels. In some embodiments, if the number of cells orpixels within a predetermined distance or area exceeds a thresholdnumber, the cells or pixels can be identified as a keyhole. For example,if there are four neighboring cells or pixels with accelerations at orabove the threshold acceleration, the four neighboring cells or pixelsare identified as a keyhole. The corresponding keyhole in a raw image, apreprocessed image, or a processed image can be labeled. The region(s)of interest, threshold acceleration, selection criteria (e.g., number ofneighboring cells or pixels, total number cells or pixels within anarea, etc.) can be selected based on the targeted features. For example,the descriptor can be modified such that five connected selected pixelswill identify a potential defect. The descriptor can utilize, withoutlimitation, segmented thresholds, selection criteria (or criterion) foridentifying potential defects (e.g., number of pixels in an area, numberof connected pixels, total number of identified pixels, etc.), or thelike.

In contrast to FIG. 24, FIG. 25 shows an image 435 corresponding to aproperly formed via 436 of FIG. 19. The central region of the image 435has a uniform intensity without any identified pixels or cells becausethe pixels or cells with the via 436 of FIG. 19 have an accelerationless than the threshold acceleration of the selection criteria. Anautomated identification routine recognizes that the via 436 does notinclude a potential defect.

Other types of speed functions and descriptors can be used. In someembodiments, the speed function R at (x, y) can be determined accordingto the equation:

$\begin{matrix}{R = \frac{1}{1 + {\alpha \lbrack {\nabla{I( {x,y} )}} \rbrack}}} & ( {{Equation}\mspace{14mu} {II}} )\end{matrix}$

where ∇I(x, y) is the gradient image intensity at (x, y) and α is aconstant which can be selected based on the detection. For example, αcan be set to 1 and increased by 1 until a desired detection isachieved. In some embodiments, the maximum integer for α can be 15 orother appropriate maximum integer. The rate function R according toequation II can make the intensity less significant in the fast marchingmethod as compared to the rate function R that is equal to theintensity. The changes of intensity rather than the intensity itselfdrive the rate function R of Equation II to provide enhanced boundarydetection of relatively noisy images or patterns. The rate can be thelowest when the gradient of intensity is the highest to facilitatedetection of features. For example, the gradient of intensity can be thehighest at boundaries to significantly extend the calculated fastmarching arrival time period within the boundary regions, to facilitatethe detection of any noisy boundary contours. Other types of speedfunctions can also be used. Elliptical functions or other types ofdescriptors can be used to find characteristics (e.g., dimensions,shapes, etc.) of detected items. In some embodiments, a descriptor inthe form of an ellipse function can be used to fit the boundarylocations detected using the speed function R of Equation II. Thus,boundary locations can be detected without counting higher intensitypixels. Additionally or alternatively, lines, curves (e.g., 1^(st) ordercurves, 2^(nd) order curves, etc.), polygons (e.g., rectangles, squares,triangles, etc.), or other fitting features can be fitted (e.g., fittedto boundary values, pixels, cells, etc.) to enhance detection.

FIG. 26 shows boxes 110 identifying vias and boxes 130 identifyingpotential defects. The boxes 130 can be automatically overlaid in theimage by identifying the potential defects using any of themethodologies described above. Some of the vias and defects are notlabeled to avoid obscuring features in the image. The image 100 can beconveniently visually inspected to evaluate the potential defects. Viaswith keyholes can be identified for discarding. If the image isimproperly labeled, a user can modify the descriptor-based analysis toincrease its accuracy. In other embodiments, potential defects can beidentified by circles, ellipses, polygons, or the like.

FIG. 27 illustrates an image 500 that includes thirteen rows of vias.The fast marching method can be used to identify vias and to evaluatethe distance, if any, between adjacent vias (e.g., adjacent vias in thesame row) to determine whether the vias are properly positioned. Theboxes identify potential stiction. For example, a box 510 identifiespotential stiction between vias 512, 514. A stiction descriptor can beselected to identify stiction based on spacing between adjacent vias(e.g., a preset distance), vias contacting one another, or the like. Thedistance between two vias can be determined and compared to a presetdistance. If the measured distance is less than the preset distance, thetwo vias are identified as a potential stiction defect. The descriptorguided fast marching analysis can also be used to evaluate spacingbetween other features (e.g., spacing between pads, semiconductorlayers, etc.).

FIG. 28 illustrates an image that includes contacts and boxes used toevaluate alignment of the contacts. An alignment descriptor can identifyrunners and contacts. A box 520 can indicate the position of runners526, 528. A box 522 can indicate the position of a contact 532. Theposition of the box 522 relative to the box 520 can be evaluated todetermine whether the contact 532 is properly positioned relative to therunners 526, 528.

FIG. 29 shows an image processing system in accordance with anembodiment of the present technology. An image processing system 550includes an imager 552 and a computing system 554. The computing system554 can analyze images captured by the imager 552 and display an outputfor viewing. The imager 552 can capture images of microelectronicdevices, such as wafers (e.g., unprocessed wafers, processed wafers,etc.), semiconductor devices (e.g., LEDs, MEMS, integrated circuitry,memory circuit, digital signal processors, etc.), or portions thereof.Wafers can be single layer wafers or multilayer wafers. In someembodiments, the imager 552 captures images of electronic devices (e.g.,LED displays, LCD displays, flat panel displays, etc.) and can include,without limitation, one or more image capture devices. Image capturedevices can include, without limitation, scanning electron microscopes,transmission electron microscopes, optical microscopes, cameras, imagingsensors, or the like. The imager 552 can be integrated into fabricationequipment or can be standalone inspection equipment. Imagers fromdifferent manufacturers may produce images with differentcharacteristics (e.g., intensity, resolution, etc.). The fast marchingmethod can be used to accurately detect features in images fromdifferent equipment manufacturers.

The computing system 554 includes memory 560, processing unit 562, and adisplay 568. Memory 560 can include, without limitation, a computerreadable medium, volatile memory, non-volatile memory, read-only memory(ROM), random access memory (RAM), or the like. The memory 560 can storeinformation, including instructions (e.g., executable code, computerprograms, etc.), reference images, correction algorithms, fast marchingalgorithms, descriptor functions, optimization programs (e.g., fastmarching optimization algorithms, descriptor function optimizationalgorithms, etc.), calibration programs, labeling protocols, databases,look up tables, or the like. For example, the memory 560 can store asequence of instructions executable by the processing unit 562.

The processing unit 562 can be in communication with the memory 560 anddisplay 568 and can include, without limitation, one or moreprogrammable processors, computers, central processing units, processingdevices, microprocessors, digital signal processors (DSPs), and/orapplication-specific integrated circuits (ASICs). The processing unit562 can execute instructions to perform the descriptor guided basedanalysis, fast marching method, etc.

The display 568 can be a liquid crystal display, LED display, or organiclight emitting diode (OLED) display. Other types of displays can also beused. A user can view results on the display 568. If the display 568 isa touchscreen, the user can manually select displayed features. In someembodiments, the computing system 554 is communicatively coupled to anetwork. A user can view images transferred via the network to a remotedisplay.

In operation, items to be inspected are delivered to the imager 552,which captures an image of the items. The processing unit 562 isconfigured to execute instructions from memory 560 to process theimages. In one embodiment, the processing unit 562 executes instructionsto automatically identify targeted features. Different instructions canbe executed to analyze different targeted features. Additionally oralternatively, results can be stored in memory 560 or transmitted via acommunication link (e.g., a computer communication link, the Internet,etc.) to a remote computer or network for viewing, storage, and/oranalysis. Results can be used to monitor performance of processingequipment (e.g., deposition equipment, sputtering equipment, CMPequipment, cluster tools, etc.).

The computing system 554 can perform self calibration. A raw image canbe sent to the processing unit 562. Information (e.g., dimensions,shapes, position, etc.) about the target feature can be stored in memoryor inputted by a user. The processing unit 562 can determine anappropriate scale to perform fast marching method. The computing system554 can match the boundaries to expected boundary sizes (e.g., diametersof vias) and can perform self calibration for new images based onvariations of scale. After the computer system 554 identifies vias, thecomputer system 554 can rapidly identify additional vias.

Certain aspects of the technology described in the context of particularembodiments may be combined or eliminated in other embodiments. Forexample, embodiments disclosed herein can be used to inspect integratedcircuitry, optoelectronics, packaging, or the like. Additionally, thefast marching method can be used to process raw images. Different typesof fast marching methods (e.g., generalized fast marching methods,classical fast marching methods, etc.) can be combined with otheranalysis techniques (e.g., level set method). For example, a portion ofan image can be processed using the fast marching method and anotherportion of the image can be processed using a level set method. Resultsfrom the fast marching method and results from the level set method canbe compared or combined. Descriptors (e.g., descriptor algorithms,descriptor functions, etc.) can be used to modify the fast marchingmethods, identify regions of an image for detailed analysis, and thelike. Further, while advantages associated with certain embodiments havebeen described in the context of those embodiments, other embodimentsmay also exhibit such advantages, and not all embodiments neednecessarily exhibit such advantages to fall within the scope of thepresent technology. Accordingly, the present disclosure and associatedtechnology can encompass other embodiments not expressly described orshown herein.

What is claimed is:
 1. A method for analyzing an image of amicroelectronic device, comprising: processing an image of amicroelectronic device using a fast marching method to obtain arrivaltime information representative of features in the image of themicroelectronic device; and analyzing the arrival time information usinga targeted feature descriptor to identify targeted features, if any, inthe image of the microelectronic device.
 2. The method of claim 1wherein processing the image of the microelectronic device comprises:identifying at least one starting area of an arrival time image of thearrival time information; and working away from the starting area tosequentially analyze the image of the microelectronic device using thefast marching method.
 3. The method of claim 1 wherein processing theimage of the microelectronic device using the fast marching methodincludes solving an Eikonal equation.
 4. The method of claim 3 whereinsolving the Eikonal equation includes converting intensities ofdifferent areas of the image to the arrival time information.
 5. Themethod of claim 1 wherein processing the image of the microelectronicdevice includes calculating the arrival time information as follows:R|∇T|=1 where R is a speed function based on intensity of the image andT is the arrival time information.
 6. The method of claim 5 wherein R isthe intensity of the image at a pixel or cell in the image.
 7. Themethod of claim 5 wherein R is calculated as follows:$R = \frac{1}{1 + {\alpha {\nabla I}}}$ where ∇I is a gradient of imageintensity and α is an integer.
 8. The method of claim 1 whereinanalyzing the arrival time information using the targeted featuredescriptor includes: processing the arrival time information using asegmentation algorithm; and identifying areas of the image of themicroelectronic device based on the processing of the arrival timeinformation using the segmentation algorithm.
 9. The method of claim 8,further comprising producing an arrival time image representative of atleast a portion of the image of the microelectronic device, and whereinprocessing the arrival time information using the segmentation algorithmincludes identifying features in the arrival time image.
 10. The methodof claim 8, further comprising identifying the targeted features in theimage of the microelectronic device for visual inspection.
 11. Themethod of claim 10 wherein the identified targeted features arepotential defects.
 12. The method of claim 1 wherein the image is ascanning electron microscope image.
 13. The method of claim 1, furthercomprising analyzing the identified targeted features by processing thearrival time information using a fast marching algorithm.
 14. The methodof claim 1 wherein processing the image of the microelectronic deviceusing the fast marching method includes: processing the image to producea first arrival time image; identifying at least one area of the firstarrival time image; and producing a second arrival time image based onthe identified area.
 15. The method of claim 14 wherein the arrival timeinformation includes the second arrival time image, and whereinanalyzing the arrival time information using the targeted featuredescriptor includes identifying features in the image of themicroelectronic device based on an analysis of the second arrival timeimage.
 16. A method for analyzing an image of a microelectronic device,comprising: selecting at least one starting area for an arrival time;processing the image of the microelectronic device using a fast marchingmethod for sequentially working away from the starting area; producingthe arrival time image based on processing of the image of themicroelectronic device; evaluating the arrival time image using atargeted feature descriptor; and identifying targeted features, if any,in the image of the microelectronic device or the arrival time image, orboth.
 17. The method of claim 16 wherein processing the image using thefast marching method includes converting intensity data of the image ofthe microelectronic device to arrival time information for producing thearrival time image.
 18. The method of claim 16 wherein processing theimage using the fast marching method includes solving the Eikonalequation for non-starting areas of the arrival time image.
 19. A methodfor identifying defects of a microelectronic device, comprising:identifying at least one starting area of an image of themicroelectronic device based on an intensity of the image of themicroelectronic device; working away from the starting area to processthe image of the microelectronic device to produce a processed imagerepresentative of the image of the microelectronic device; evaluatingthe processed image using a defect descriptor; identifying one or morefeatures in the processed image using the defect descriptor; andidentifying potential defects of the microelectronic device based on theidentified one or more features.
 20. The method of claim 19 whereinidentifying the features includes identifying boundaries of featuresbased on intensity.
 21. The method of claim 19 wherein identifying thefeatures includes producing a segmented image based on the processedimage.
 22. The method of claim 19 wherein working away from the startingarea includes converting intensity data of the image of themicroelectronic device to arrival time information using a fast marchingmethod.
 23. The method of claim 19 wherein evaluating the processedimage using the defect descriptor includes segmenting the image based onat least one threshold value of intensity.
 24. The method of claim 19wherein evaluating the processed image includes fitting boundariesutilizing at least one of an elliptical function, a line, a curve,and/or a polygon.
 25. A system for analyzing images, comprising: memorycontaining instructions; and a programmable processing unit configuredto execute instructions from the memory to: process an image of amicroelectronic device using a fast marching method to obtain arrivaltime information representative of a feature of the microelectronicdevice; and analyze the arrival time information using a targetedfeature descriptor to identify targeted features, if any, in the imageof the microelectronic device.
 26. The system of claim 25 wherein theprogrammable processing unit is configured to execute the instructionsto: identify at least one starting area of the image; and work away fromthe starting area to sequentially analyze other areas of the image usingthe fast marching method.
 27. The system of claim 26 wherein workingaway from the starting area to sequentially analyze other areas of theimage comprises converting intensity data of the image to the arrivaltime information.
 28. The system of claim 25, further comprising ascanning electron microscope communicatively coupled to the programmableprocessing unit.
 29. The system of claim 25, wherein the programmableprocessing unit is configured to execute the instructions to: produce anarrival time image representative of at least a portion of themicroelectronic device based on processing of the image of amicroelectronic device; and evaluate the arrival time image based on thedefect descriptor; and identify targeted features, if any, in the imageof the microelectronic device or the arrival time image, or both.